U.S. patent application number 17/168048 was filed with the patent office on 2021-08-05 for extremely electrically small antennas based on multiferroic materials.
This patent application is currently assigned to THE REGENTS OF THE UNIVERSITY OF CALIFORNIA. The applicant listed for this patent is THE REGENTS OF THE UNIVERSITY OF CALIFORNIA. Invention is credited to Gregory P. Carman, Jinzhao Hu, Joseph Devin Schneider, Abdon E. Sepulveda, Sidhant Tiwari, Elmer Wu, Wenzhong Yan, Zhi Yao.
Application Number | 20210242606 17/168048 |
Document ID | / |
Family ID | 1000005568904 |
Filed Date | 2021-08-05 |
United States Patent
Application |
20210242606 |
Kind Code |
A1 |
Sepulveda; Abdon E. ; et
al. |
August 5, 2021 |
EXTREMELY ELECTRICALLY SMALL ANTENNAS BASED ON MULTIFERROIC
MATERIALS
Abstract
A multiferroic antenna apparatus and method are described which
provides increased energy efficiencies and ease of implementation.
Magnetoelastic and/or magnetostrictive resonator are coupled to a
piezoelectric substrate, along with electrodes coupled to its
opposing surfaces. In receive mode the resonators create mechanical
waves in response to being excited into magnetic oscillation by
receiving electromagnetic radiation, and these mechanical waves
coupled to the piezoelectric substrate causing it to generate an
electrical output signal at said electrodes. In transmit mode an
electrical signal coupled through the electrodes induces mechanical
waves in the piezoelectric substrate directed to the resonators
which are excited into magnetic oscillation to output
electromagnetic waves.
Inventors: |
Sepulveda; Abdon E.; (Los
Angeles, CA) ; Carman; Gregory P.; (Los Angeles,
CA) ; Hu; Jinzhao; (Los Angeles, CA) ;
Schneider; Joseph Devin; (Los Angeles, CA) ; Wu;
Elmer; (Rowland Heights, CA) ; Yao; Zhi; (Los
Angeles, CA) ; Tiwari; Sidhant; (Riverside, CA)
; Yan; Wenzhong; (Los Angeles, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THE REGENTS OF THE UNIVERSITY OF CALIFORNIA |
Oakland |
CA |
US |
|
|
Assignee: |
THE REGENTS OF THE UNIVERSITY OF
CALIFORNIA
Oakland
CA
|
Family ID: |
1000005568904 |
Appl. No.: |
17/168048 |
Filed: |
February 4, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/US2019/045865 |
Aug 9, 2019 |
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17168048 |
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62880513 |
Jul 30, 2019 |
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62716936 |
Aug 9, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01Q 21/067 20130101;
H01Q 3/44 20130101 |
International
Class: |
H01Q 21/06 20060101
H01Q021/06; H01Q 3/44 20060101 H01Q003/44 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0003] This invention was made with government support under Grant
Number 1160504, awarded by the National Science Foundation, and
Grant Number FA9550-16-C-0029, awarded by the U.S. Air Force,
Office of Scientific Research. The government has certain rights in
the invention.
Claims
1. A multiferroic radio frequency antenna apparatus, comprising: a
piezoelectric substrate; at least one pair of electrodes coupled to
said piezoelectric substrate; and a plurality of magnetoelastic
and/or magnetostrictive resonators coupled to said piezoelectric
substrate; wherein said electrodes in combination with
piezoelectric substrate convert between radio frequency electrical
signals input at the electrodes to mechanical waves in the
piezoelectric substrate, or from mechanical waves in the
piezoelectric substrate to radio frequency electrical signal from
the electrodes; wherein said magnetoelastic and/or magnetostrictive
resonators in combination with said piezoelectric substrate convert
between radio frequency electromagnetic waves input at said
magnetoelastic and/or magnetostrictive resonators to mechanical
waves in said piezoelectric substrate, or from mechanical waves in
said piezoelectric substrate to radio frequency electromagnetic
waves from said magnetoelastic and/or magnetostrictive resonators;
and wherein said antenna apparatus performs reception in response
to converting radio frequency electromagnetic radiation into radio
frequency electrical signals, and performs transmission in response
to converting radio frequency electrical signals into radio
frequency electromagnetic radiation.
2. A multiferroic radio frequency antenna apparatus, comprising: a
piezoelectric substrate; at least one pair of electrodes, coupled
to said piezoelectric substrate, and configured for converting
between an electrical signal at the electrodes to mechanical waves
in the piezoelectric substrate, or from mechanical waves in the
piezoelectric substrate to electrical signals at the electrodes;
and a plurality of magnetoelastic and/or magnetostrictive
resonators, coupled to said piezoelectric substrate, and configured
for converting between mechanical waves in the piezoelectric
substrate to electromagnetic waves from the magnetoelastic and/or
magnetostrictive resonators, or from electromagnetic waves received
by the magnetoelastic and/or magnetostrictive resonators into
mechanical waves in the piezoelectric substrate; wherein said
piezoelectric substrate interfaces between said at least one pair
electrodes and said plurality of magnetoelastic and/or
magnetostrictive resonators to transmit electromagnetic signals by
converting radio frequency electrical signals applied at said
electrodes into electromagnetic waves from the magnetoelastic
and/or magnetostrictive resonators, and to receive electromagnetic
signals by converting electromagnetic waves received at said
magnetoelastic and/or magnetostrictive into radio frequency
electrical signals at said electrodes.
3. A multiferroic radio frequency antenna apparatus, comprising: a
piezoelectric substrate; a plurality of magnetoelastic and/or
magnetostrictive resonators coupled to said piezoelectric
substrate; at least one pair of electrodes, having a first
electrode coupled to a first surface plane of said piezoelectric
substrate, and a second electrode coupled to a second surface plane
of said piezoelectric substrate; wherein in receive mode said
plurality of magnetoelastic and/or magnetostrictive resonators
create mechanical waves in response to being excited into magnetic
oscillation by receiving electromagnetic radiation, and these
mechanical waves coupled to the piezoelectric substrate cause it to
generate an electrical output signal at said electrodes; and
wherein in transmit mode an electrical signal coupled through said
electrodes to the piezoelectric substrate induces mechanical waves
directed to said plurality of magnetoelastic and/or
magnetostrictive resonators which are excited into magnetic
oscillation to output electromagnetic waves.
4. The apparatus of any of claims 1-3, wherein said antenna
apparatus is configured for transmitting or receiving radio
frequency electromagnetic radiation.
5. The apparatus of any of claims 1-3, wherein dynamic magnetic
flux current oscillations in said plurality of magnetoelastic
and/or magnetostrictive resonators are used as a fundamental source
for detecting or radiating radio frequency electromagnetic
waves.
6. The apparatus of any of claims 1-3, wherein wavelengths of the
mechanical waves in said piezoelectric substrate are orders of
magnitude smaller than wavelengths of the radio frequency
electromagnetic waves which are received or transmitted from said
magnetoelastic and/or magnetostrictive resonators, allowing said
antenna apparatus to be orders of magnitude smaller than a
conventional electromagnetic antenna operating at an identical
radio frequency.
7. The apparatus of any of claims 1-3, wherein said electrodes
comprise a first electrode coupled to a first surface plane of said
piezoelectric substrate, and a second electrode coupled to a second
surface plane of said piezoelectric substrate.
8. The apparatus of claim 7, wherein said first electrode or said
second electrode is configured in a pattern with open spaces within
each of which are disposed an array of magnetoelastic and/or
magnetostrictive resonators.
9. The apparatus of any of claims 1-3, wherein said piezoelectric
substrate uses dynamic strain in converting between electrical
signals and mechanical waves.
10. The apparatus of any of claims 1-3, wherein said mechanical
waves comprise a shear wave.
11. The apparatus of any of claims 1-3, wherein said plurality of
magnetoelastic and/or magnetostrictive resonators are configured to
transfer between electromagnetic waves and mechanical waves in
response to their natural frequency.
12. The apparatus of claim 11, wherein size, shape, and distance
relationships between said plurality of magnetoelastic and/or
magnetostrictive resonators and said electrodes determine the
resonant parameters.
13. The apparatus of any of claims 1-3, wherein said electrodes
comprise a detector for measuring voltage and generating an output
to a grounded coplanar waveguide.
14. The apparatus of any of claims 1-3, wherein said mechanical
waves comprise a shear wave, or a shear-horizontal wave, or a lamb
wave, or any combination of shear wave, shear horizontal wave and
lamb wave.
15. The apparatus of any of claims 1-3, further comprising
incorporating islands of floating magnetoelastic (ME) material
between at least one pair of electrodes.
16. The apparatus of any of claims 1-3, further comprising an
antenna switching circuit configured for switching m
radio-frequency sources or inputs, between n different multiferroic
antennas in response to receiving at least one control voltage in a
time varying antenna, wherein value n is larger than m.
17. The apparatus of claim 16, wherein at least a portion of said n
different multiferroic antennas operate at different frequency
ranges, toward broadening frequency range of said multiferroic
radio frequency antenna apparatus to reach broad band
radiation.
18. A method of generating electromagnetic radiation at radio
frequencies into free space, comprising: utilizing magnetoelastic
and/or magnetostrictive material as resonators to create or receive
mechanical waves across a piezoelectric substrate to electrodes
upon which an electrical signal is created or received.
19. The method of claim 18, further comprising incorporating
mechanical acoustic energy reflecting mechanisms toward enhancing
mechanical wave strength and/or electrical signal strength.
20. The method of claim 19, wherein said mechanical acoustic energy
reflecting mechanisms are selected from the group of mechanical
acoustic energy reflecting mechanisms consisting of Bragg acoustic
mirrors, acoustic gratings, trenches, and air cavities, toward
enhancing mechanical wave strength and/or electrical signal
strength.
21. The method of claim 18, wherein said mechanical waves comprise
a shear wave, or a shear-horizontal wave, or a lamb wave, or any
combination of shear wave, shear horizontal wave and lamb wave.
22. The method of claim 18, further comprising incorporating
islands of floating magnetoelastic (ME) material between at least
one pair of electrodes.
23. The method of claim 18, further comprising switching n
different multiferroic antennas between m radio-frequency sources
or inputs, in response to receiving at least one control voltage in
controlling a time varying antenna, in which value n is larger than
value m.
24. The method of claim 23, wherein at least a portion of said n
different multiferroic antennas are configured for operating at
different frequency ranges than one another, toward broadening
overall an range of operating frequencies.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to, and is a 35 U.S.C.
.sctn. 111(a) continuation of, PCT international application number
PCT/US2019/045865 filed on Aug. 9, 2019, incorporated herein by
reference in its entirety, which claims priority to, and the
benefit of, U.S. provisional patent application Ser. No. 62/716,936
filed on Aug. 9, 2018, incorporated herein by reference in its
entirety, and which also claims priority to, and the benefit of,
U.S. provisional patent application Ser. No. 62/880,513 filed on
Jul. 30, 2019, incorporated herein by reference in its entirety.
Priority is claimed to each of the foregoing applications.
[0002] The above-referenced PCT international application was
published as PCT International Publication No. WO 2020/101773 A2 on
May 22, 2020, which publication is incorporated herein by reference
in its entirety.
INCORPORATION-BY-REFERENCE OF COMPUTER PROGRAM APPENDIX
[0004] Not Applicable
NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION
[0005] A portion of the material in this patent document may be
subject to copyright protection under the copyright laws of the
United States and of other countries. The owner of the copyright
rights has no objection to the facsimile reproduction by anyone of
the patent document or the patent disclosure, as it appears in the
United States Patent and Trademark Office publicly available file
or records, but otherwise reserves all copyright rights whatsoever.
The copyright owner does not hereby waive any of its rights to have
this patent document maintained in secrecy, including without
limitation its rights pursuant to 37 C.F.R. .sctn. 1.14.
BACKGROUND
1. Technical Field
[0006] The technology of this disclosure pertains generally to
electrically small antennas, and more particularly to surface
acoustic wave (SAW) multiferroic antennas, bulk acoustic wave (BAW)
multiferroic antennas, shear-horizontal (SH) wave multiferroic
antennas and lamb wave multiferroic antennas.
2. Background Discussion
[0007] Conventional antennas rely on electrical currents
oscillating to generate electromagnetic radiation at radio
frequencies into free space. However, a conventional antenna
exhibits low radiating capability when placed near a conductive
plane due to a platform effect. At the same time, when made into a
small size, the antenna will have significantly higher Ohmic
losses. This is due to the effect that as the physical dimensions
are reduced, the device resistance increases.
[0008] Recently, research into the field of multiferroic
magnetoelectric composite structures have gained attention due to
their energy efficiency and wide application area. However, these
multiferroic antenna designs still have issues in attaining
practical levels of energy efficiency and ease of manufacture when
implementing physical real-life antenna arrays.
[0009] Accordingly, a new multiferroic antenna structure is needed
which is readily manufactured that overcomes energy efficiency
issues. The present disclosure fulfills that need and provides
additional advantages of existing technology.
BRIEF SUMMARY
[0010] The technology described in this disclosure generally
pertains to radio frequency antennas, and more particularly, to a
mechanical mediated multiferroic antenna for radio frequencies.
Multiferroic antennas include the subclass of surface acoustic wave
(SAW) antennas, bulk acoustic wave (BAW) antennas, shear-horizontal
(SH) wave antennas and lamb wave antennas that radiate or receive
radio frequencies using a nano/micro-scale structure.
[0011] A new multiferroic antenna is described which uses dynamic
magnetic flux current oscillations as the fundamental source for
detecting or radiating EM waves. An aspect of the technology is to
provide a new path to couple mechanical waves, which are mainly but
not limited to mechanical waves, with EM waves.
[0012] Further aspects of the technology described herein will be
brought out in the following portions of the specification, wherein
the detailed description is for the purpose of fully disclosing
preferred embodiments of the technology without placing limitations
thereon.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0013] The technology described herein will be more fully
understood by reference to the following drawings which are for
illustrative purposes only:
[0014] FIG. 1 is a block diagram illustrating the operation of a
multiferroic antenna according to an embodiment of the present
disclosure.
[0015] FIG. 2 is a schematic showing the relationship of the EM
wave, resonators and electrodes in a multiferroic antenna according
to an embodiment of the present disclosure.
[0016] FIG. 3 is a schematic showing geometry and dimensions of
electrode and resonator elements in a multiferroic antenna
according to an embodiment of the present disclosure.
[0017] FIG. 4 is a schematic showing the structure of the electrode
array in a multiferroic antenna implemented according to an
embodiment of the present disclosure.
[0018] FIG. 5 is a schematic showing the structure of a
multiferroic antenna array according to an embodiment of the
present disclosure.
[0019] FIG. 6 is a schematic cross-sectional view of the
multiferroic antenna shown in FIG. 5 according to an embodiment of
the present disclosure.
[0020] FIG. 7A through 7C are a schematic and test results for a
multiferroic antenna implemented according to an embodiment of the
present disclosure.
[0021] FIG. 8 is a schematic of a shear-horizontal (SH) wave or
lamb wave multiferroic antenna according to an embodiment of the
present disclosure.
[0022] FIG. 9 is a schematic of a shear-horizontal (SH) wave or
lamb wave high density mode multiferroic antenna according to an
embodiment of the present disclosure.
[0023] FIG. 10 is a schematic of a bulk acoustic wave (BAW) solidly
mounted resonator multiferroic antenna according to an embodiment
of the present disclosure.
[0024] FIG. 11A through FIG. 11D are schematics and characteristics
of a multiferroic antenna according to an embodiment of the present
disclosure.
[0025] FIG. 12 is a schematic of a switching circuit for operating
arrays of multiferroic antennas in a time varying manner according
to an embodiment of the present disclosure.
[0026] FIG. 13A and FIG. 13B are plots of return loss and strain of
a multiferroic antenna operating according to an embodiment of the
present disclosure.
DETAILED DESCRIPTION
1. Introduction
[0027] An antenna is described, by way of example and not
limitation, which relies on magnetoelastic and/or magnetostrictive
resonators to transmit electromagnetic waves through dynamic
strain, or to receive electromagnetic waves when such a dynamic
strain is induced on a piezoelectric substrate. The magnetoelastic
and/or magnetostrictive resonators can only transfer certain
frequency EM waves into mechanical vibrations related to their
natural frequency of resonance. The size, shape, and distance
relationship between the resonator and its receiver/detector
electrode determine the resonant parameters, which are conditions
for peak voltage detection. A feature of this antenna is that the
resonators are in the same plane with the electrode detectors, but
in a different plane with the ground electrode. The electrical
field is applied out-of-plane and the strength of such a field is
detected through measuring the induced voltage. In this way, the
energy loss will be reduced, and the signal will be more
efficiently detected.
[0028] To overcome issues associated with conventional antennas,
the present disclosure utilizes a magnetic current instead of an
electrically conductive current. In one embodiment, an antenna
according to the present disclosure comprises resonators comprising
magnetoelastic/magnetostrictive materials (which can include Ni,
Co, Fe), alloy (which may include FeGaB, CoFe, NiFe, CoNi, FeNiCo,
CoNiFe, Metglas, FeSi, CoSiB, Galfenol, FeCoSiB, CoFeB, TbFe.sub.3,
TbFe.sub.2, DyFe.sub.2, Terfenol-D, CoFe, AlFe, CoCrPt, CoCr,
CoCrB, FeCrB, Fe.sub.3O.sub.4, CoFe.sub.2O.sub.4,
MnZnFe.sub.2O.sub.4, NiFe.sub.2O.sub.4, Y.sub.3Fe.sub.5O.sub.12,
YIG, NiZnFeO, MnNiZnFe or FeCoSiB) or composites (which can include
FeGa/NiFe multilayers). The present disclosure is not limited to
the above materials or combinations thereof, as other materials and
combinations can exhibit similar properties. It should be
appreciated that Magnetostrictive materials are ferromagnetic
materials that change shape in response to application of a
magnetic field, and that Magnetoelastic materials change their
elastic properties and extension in response to application of a
magnetic field. The technology is applicable to antennas in general
and is not limited by the size, shape or distance relationship
between the resonator and the corresponding electrode
detectors.
[0029] In at least one embodiment the presented technology is an
electrically small antenna that utilizes magnetoelastic and/or
magnetostrictive material as resonators to create mechanical waves
that include, but are not limited to, shear waves, shear-horizontal
wave and lamb wave across a piezoelectric substrate, which by way
of example and not limitation may comprise Lithium Niobate, Quartz,
Aluminum Nitride (AlN), PZT, ZnO, LiTaO or PMN-PT, or other
materials which produce an electrical signal. In at least one
embodiment, the magnetoelastic/magnetostrictive resonators are
coupled with a piezoelectric substrate as well as an electrode
detector fabricated from conductive materials, such as Gold,
Silver, Copper, Aluminum or other suitable conductor.
[0030] It should be appreciated that the phrasing "and/or" is used
herein to indicate elements A and B, or either element A or B; and
if more than two elements are described then it indicates A and B
and C, any of these elements separately, or any combination of A, B
and C.
[0031] The magnetoelastic/magnetostrictive resonators perform as a
source to excite the mechanical wave through the piezoelectric
substrate while the electrode structures act as a detector to
measure the mechanical wave-induced electrical field. The
structure, as a whole, can be used to convert electromagnetic
radiation into an electric signal, or vice versa to convert
electrical signals into electromagnetic radiation.
[0032] Accordingly the present disclosure provides for transmitting
or receiving electromagnetic (EM) radiation with extremely
electrically small structures. The receiving process can be
generally described as follows: (1) an EM wave comes from free
space; (2) the EM wave excites magnetic oscillation in
magnetoelastic material; (3) the magnetoelastic material islands
mechanically oscillate and launch mechanical waves in the
piezoelectric substrate; (4) The piezoelectric substrate transduces
the shear wave or other potential mechanical wave into voltage
changes; and (5) the voltage is measured with an optimized
electrode design and output to a grounded coplanar waveguide.
[0033] The transmitting process is the converse of the above, as
follows: (1) voltage is applied to an optimized electrode design;
(2) a piezoelectric substrate transduces the applied voltage
changes into a shear wave or other potential mechanical wave; (3)
mechanical waves in the piezoelectric substrate reach the
magnetoelastic material islands which mechanically oscillate; (4)
mechanical oscillation in the magnetoelastic material generate
electromagnetic waves (EM); (5) EM waves are launched into free
space.
[0034] Further aspects of the technology described herein will be
brought out in the following portions of the specification, wherein
the detailed description is for the purpose of fully disclosing
preferred embodiments of the technology without placing limitations
thereon.
[0035] The geometry of the resonators (size and shape) as well as
the architecture of the array (e.g., spacing between resonators and
distance between resonators and electrodes, and can include
different architectures for each row of the resonator array) are
determined by maximizing the output voltage, while global
optimization is performed toward avoiding poor local maxima.
[0036] Acoustic energy reflecting components can be potentially
used in this structure. The acoustic energy reflecting components
include, but are not limited to, Bragg acoustic mirror and acoustic
gratings. More particularly, a Bragg acoustic mirror is a set of
multilayers formed by different material with different acoustic
impedance. In a Bragg mirror, the thickness of each layer is
designed to be .lamda./4 where .lamda. is the wavelength of a
longitudinal wave or shear wave in the corresponding layer.
Acoustic gratings are a set of comb-shaped structures of elongated
strips that are formed by one material or different materials. The
width of each grating and the distance between different grating
elements can be .lamda./4 or .lamda./2. Typical materials which can
be utilized for acoustic energy reflecting components include but
are not limited to Al, W, AlN, SiO.sub.2, Si, SiN, and Mo. The
energy reflecting components may also comprise trenches or air
cavities surrounding the multiferroic antenna.
[0037] The transduction process in receiving mode is detailed as
follows. (1) An electromagnetic wave reaching the device results in
a magnetic flux and/or current applied to the magnetoelastic or
magnetostrictive resonators. (2) The applied flux and/or current
then causes the resonator to oscillate accordingly. (3) Surface
resonator oscillations excite a mechanical wave, which
substantially comprises, but is not limited to, a shear wave across
the thickness of a piezo electric substrate. (4) These mechanical
waves create an oscillating voltage difference between the top
surface, upon which the electrode detector rests, and the bottom
surface that is grounded. (5) The frequency of both the mechanical
wave and the resulting oscillating electric potential matches the
frequency of the initial electromagnetic wave. (6) The above
process can also be reversed, starting with the electric potential
and ending with the radiated electromagnetic wave.
[0038] By way of example and not limitation, the following
describes a specific design example, implemented for a frequency of
300 MHz and utilizing rectangular shaped resonators. In this
example, the material of the design is Nickel (Ni) for the
resonators, Gold (Au) for the electrodes, and Lithium Niobate
(LiNbO3) for the piezoelectric substrate. It will be appreciated,
however, that this disclosure is not limited to the specific
example with its described shape, size, area, thickness, applicable
bandwidth, other structural features and design criterion, but the
present disclosure is applicable to all multiferroic antennas based
on the presented technology. The described design procedure can
easily accommodate a range of forcing frequencies and combination
of materials.
[0039] A key aspect of the technology, which allows for reducing
antenna size, is the ability to transfer an electromagnetic wave
from free space into a transmissible mechanical wave. It will be
recognized that for the same given frequency the wavelength of the
mechanical wave will be hundreds of times smaller than the original
electromagnetic wave, thus allowing it to be detected by a
structure many times smaller than a standard antenna.
2. Multiferroic Antenna Embodiments
[0040] FIG. 1 illustrates an example embodiment 10 of the
transduction process of the multiferroic antenna according to the
present disclosure. The electromagnetic (EM) waves 12 excite the
magnetic flux oscillating within the magnetoelastic-material-based
resonators 14. The resonators that are patterned on the
piezoelectric substrate (e.g., the top of substrate) will also
mechanically oscillate 16 due to the magnetoelastic effect. A
mechanical wave is also induced across the piezoelectric substrate
18 that is attached to the resonator. Because of the piezoelectric
effect, the substrate will transfer the mechanical wave to an
electrical signal 20 through a voltage difference. This process is
reversible, which means this antenna can both receive and radiate
an EM wave signal.
[0041] FIG. 2 illustrates an example embodiment 30 of a
multiferroic antenna array. A piezoelectrical substrate 32 has a
ground electrode 34 on a first surface (e.g., on the bottom
surface). On the opposing surface (e.g., top surface) are depicted
magnetoelastic-material-based resonators 36a, 36b, 36c (also
referred to as magnetic islands in FIG. 6) and one or more
detecting electrodes 40 as well are deposited and patterned. Cone
39 is a schematic representation of magnetization oscillation in
the region of square 38 which represents part of a magnetoelastic
resonator. A voltage source/sink is depicted connected between the
electrode(s) 40 and ground electrode 34. It should be appreciated
that the figures only depict a representative portion of a
multiferroic antenna array, however, the size of the components and
the distances between the components can be varied in response to
the use of different materials, operating frequency or other design
criterion without departing from the teachings of the present
disclosure.
[0042] In FIG. 2 is also shown the working principle of this
antenna with an EM wave 42 shown reaching resonators 36a through
36c, resulting in a wave created by the resonators and then
transferred 43 through the piezoelectric substrate 32. Next, the
piezoelectric substrate translates the mechanical wave into an
out-of-plane voltage signal 44, which is captured by electrodes on
the top surface 40 as well as the ground electrodes on the bottom
surface 34. Any desired plurality of these multiferroic antenna
structures can be placed adjacent to one another, such as in a
periodic form, to implement a multiferroic antenna array to attain
a desired level of radiation power/signal strength. One of the
principle advantages of the present disclosure in relation with
conventional magnetoelastic frequency antennas is the signal
strength. This presented technology relies on the out-of-plane
electrical field and mechanical wave, which allows the detection
electrodes to be positioned in close proximity to the
magnetoelastic/magnetostrictive resonators. The short distance
avoids the energy loss through the transfer process and the
interference between different resonators, while allowing large
scale integrated antenna arrays to be fabricated.
[0043] FIG. 3 illustrates an example embodiment 50 of a pattern of
electrodes and resonators for the exemplified multiferroic antenna.
Rows of resonators are shown 52a through 52n, 54a through 54n and
56a through 56n, with one row between each pair of electrodes 58,
60. The conductive electrodes 58, 60 are exemplified as being
fabricated from Gold/Au and having a width 61 of 24.2 .mu.m, the
dimensions for the resonators (e.g., from Nickel/Ni material) are
exemplified as having a width 62 of 65.2 .mu.m and height 64 of 9.6
.mu.m with a thickness of 250 nm. In this example, the
resonator-to-resonator spacing 66 is 70 .mu.m, with the
resonator-to-electrode spacing 68 exemplified as 71.4 .mu.m. There
is only one row of resonators between two detector electrodes.
[0044] Toward accommodating different applications, operating
frequencies and materials, the width and length of the resonators
as well as the spacing between different components can range from,
but is not limited to, a size range from about 1 .mu.m to about 100
.mu.m. The thickness of the resonators can range from, but is not
limited to, a size range from about 10 nm to about 2 .mu.m. In at
least one multiferroic antenna embodiment, different resonators
(e.g., differing in size, shape and material) can be employed for
expanding the operating bandwidth, increasing signal strength or
for other purposes. The piezoelectric material may comprise any
suitable material such as z-cut Lithium Niobate. The thickness of
the piezoelectric substrate in this example embodiment is
approximately 100 .mu.m. However, the thickness for the disclosed
technology can range from, but is not limited to, approximately 10
nm to about 2 mm. The fabrication process can be, but is not
limited to photolithography, lift off, e-beam evaporation or
magnetic control sputtering in a cleanroom.
[0045] FIG. 4 illustrates an example embodiment 70 of an electrode
array depicted in plan view. The width of the functional electrodes
76 is designed for optimum impedance matching to the feed circuit,
while the gap between the electrodes is designed to maximize signal
strength. The relative position 78 of the resonators (not seen due
to small size in this depiction) is optimized, designed and
determined after the electrode array is fixed. The functional
electrodes are connected by the package electrodes 72, 74 on the
side, which connects the device to the feed circuit through bonding
wires. The figure also depicts the use of alignment markers 80 for
aligning the resonators.
[0046] FIG. 5 illustrates an example embodiment 90 of the antenna,
depicted in plan view. Resonators are patterned between the
electrodes. Every single resonator as well as the adjacent
electrodes comprise a singular small antenna, an antenna array is
deployed to increase the signal strength and includes redundancy to
accommodate fabrication tolerances. Different levels of signal
strength can be obtained by antenna arrays spanning any desired
amount of surface area.
[0047] FIG. 6 illustrates an example multiferroic antenna
embodiment 110 which corresponds to a portion of FIG. 5. A ground
electrode 112 is seen beneath piezoelectric substrate 114, over
which are electrodes 116 and magnetic islands 118. Induced or
sensed EM wave 122 and magnetic field area (+/-H field) 120 for
sensing/generating the EM wave are also shown in the figure.
[0048] FIG. 7A through FIG. 7C illustrate an example embodiment of
an antenna 130 and associated preliminary test results 140, 150. In
the antenna shown in FIG. 7A, the longitudinal field 132 and
transverse field 134 signals were measured, in this example using
an Agilent.RTM. N5230C PNA-L Network Analyzer. In this test, the
transmitting antenna was a loop antenna, with a diameter of
approximately 3 cm, and the antenna was the multiferroic antenna
under test (AUT), with size about 7.times.5 mm.sup.2. In this
example the longitudinal field is the preferred field, since the
field direction tends to align the magnetization in the
magnetoelastic resonators, providing improved resonant performance.
S11 in FIG. 7B depicts return loss of the AUT, while S12 in FIG. 7C
shows the ratio between the received power to the transmitted
power. If the field is aligned in the longitudinal direction the
signal will be at its highest. If the field is transverse, the
material will be stiffer. The resulting frequency will be higher,
and the signal will be weaker. These results confirm that the
produced signal is due to the magnetoelastic effect of the antenna
array described in the present disclosure.
[0049] As can be seen, the presented technology is a new
multiferroic antenna based on a mechanical/shear wave. With this
technology, the size of the singular small antenna can be created
with dimensions approximately 1/10000 of the wavelength (.lamda.).
The size of the antenna, and/or array of antennas, can be scaled
such as to under 1/100.lamda. to reach a practical signal strength
for a given application. This multiferroic antenna is suitable for,
but not limited to, applications for military (e.g., approximately
200 MHz to 300 MHz) or medical (e.g., approximately 400 MHz)
devices. In view of its small scale, this antenna can be implanted
into various types of medical equipment. The ability to provide
relatively low frequency operation ensures the signal can safely
pass through organic tissues. The antenna of the present
disclosure, however, can be configured for any desired frequency
range as its geometric dimensions, shape or other parameters, as
well as the design of electrodes can be readily changed.
3. Multiferroic Antenna Enhanced by Energy Reflecting
Components
[0050] Based on a mechanical wave resonator, previously designed
multiferroic antennas have high energy dissipation making it
difficult to attain a signal strength which is useful for practical
applications. In this disclosure energy reflecting components are
harnessed, such as acoustic Bragg mirrors, acoustic gratings,
trenches and air cavities, to confine the energy and form standing
waves to strengthen resonator vibrations, and alternatively to
enhance radiated signal strength as well.
[0051] FIG. 8 through FIG. 10 illustrate example embodiments 170,
190 and 210 of a shear-horizontal/lamb wave multiferroic antenna
design in FIG. 8, a shear-horizontal/lamb wave high density mode
multiferroic antenna design in FIG. 9, and a bulk acoustic wave
(BAW) solidly mounted resonator multiferroic antenna design in FIG.
10.
[0052] Although different, each of these designs employ the same
working principle, which is to employ mechanical waves to oscillate
the magnetic dipoles in a magnetic material to generate
electromagnetic (EM) waves, and vice versa. The mechanical wave is
generated and detected through piezoelectric components. The EM
wave is induced and sensed by magneto-elastic elements. In this
way, an electrical signal is transferred into an EM wave. The
system is designed to operate at the mechanical resonance frequency
of the structure. All three of these multiferroic antenna designs
use the aforementioned energy reflecting components to confine the
energy and form standing waves in the structure. Their sizes can be
modified to match different operating frequencies.
[0053] In FIG. 8 a multiferroic antenna 170 is illustrated as a
shear-horizontal wave/lamb wave antenna with Si substrate 172,
acoustic Bragg mirror stack 174, upper layer of piezoelectric
substrate 176, and plate electrode 178 underneath the AlN layer
176. An upper structure 182 is depicted having comb-shaped
electrodes 184 (represented material: Al), and magnetoelastic
material 186 (represented material: Ni) stripes, and acoustic
gratings 180a, 180b (fabricated from high acoustic impedance
material, represented material: W) pattered on the top of the
piezoelectric substrate (represented material: AlN). The figure is
shown with voltage source/sense 188 and ground connection 189.
[0054] In FIG. 9 is a multiferroic antenna 190 having a
shear-horizontal wave/lamb wave antenna high density mode design
shown with Si substrate 192, acoustic Bragg mirror stack 194, upper
layer of piezoelectric substrate 196, and plate electrode 198. An
upper structure 199 is depicted having comb-shaped electrodes 200
(represented material: Al), and magnetoelastic material 202
(represented material: Ni) stripes pattered on the top of the
piezoelectric substrate (represented material: AlN). Between each
set of multiferroic antennas in the array are trenches 204, for
instance trenches fabricated by etching the piezoelectric substrate
and/or the Bragg lattice. The figure is shown with voltage
source/sense 206 and ground connection 208.
[0055] In FIG. 10 is a multiferroic antenna 210 having a solidly
mounted resonator design with Si substrate 212, acoustic mirror
stack 214, upper layer of AlN 216, and voltage source/sense and
ground 226, 228. Bus-connected electrodes 220 (represented
material: Al) are pattered on the top of the piezoelectric
substrate (represented material: AlN). The piezoelectric substrate
and/or the Bragg acoustic mirror is etched to form trenches 224
which match the shape of the electrodes. On the top of the
electrodes, the magnetoelastic material 222 (represented material:
Ni) block is patterned.
[0056] For these three example designs, the ground electrode is
coupled on the back side of the piezoelectric substrate, under
which there is a set of layers for a Bragg acoustic mirror formed
by alternating high and low acoustic impedance material
multilayers. The thickness of each layer, including high/low
acoustic impedance materials, piezoelectric substrate electrodes,
and magnetoelastic material can be modified independently to match
the targeted frequency. The whole system can be patterned on the
top of the substrate, such as comprising Si material, or directly
on the shell of other devices. In at least one embodiment a biasing
structure (not shown) is utilized for applying a bias magnetic
field to enhance signal strength. The bias magnetic field can be
provided either by a permanent magnet or a tunable electrically
magnet. The number of stripes can be modified and the number of
antennas on one chip can also be altered, wherein its
implementation is not limited to those configurations depicted in
the figures. The structure can be periodically patterned on the
desired area. The fabrication process consists of photolithography,
lift off, e-beam evaporation, magnetron sputtering, and etching in
the cleanroom.
[0057] It should be appreciated that the present disclosure
contemplates the combination of elements from FIG. 8 through 10 as
well as other reflective structures and materials used in various
combinations to achieve similar signal performance
improvements.
[0058] This antenna can receive/transmit electromagnetic radiation
with extremely small chips/structures. Traditional antennas require
geometries that must be on the order of a wavelength to maximize
their efficiency. Since the wavelength for the mechanical wave is
thousands of times smaller than EM wave, this antenna is roughly a
hundredth of a wavelength (of EM wave), which means that it can be
used on devices with limited real-estate (i.e., cell phones, UAV,
wearable, and bio-implantable devices). In addition, this
electrically small antenna can operate at relatively low
frequencies (e.g., hundreds of MHz regime) without increasing chip
size.
[0059] Enhanced by energy reflecting components, this antenna
signal has the potential to be the strongest among existing
electrically small antennas. Furthermore, the fabrication process
only requires the use of mature technologies. The design has a high
defect/imperfection tolerance and is easily mass producible.
4. Bragg Mirror and Multiple Frequency Operation
[0060] One of the issues with traditional multiferroic antennas is
that most of the strain energy does not translate into magnetic
energy due to propagation of mechanical waves outside the
magnetoelastic zone. In at least one embodiment, the present
disclosure incorporates a Bragg acoustic mirror to solve this
problem.
[0061] A Bragg acoustic mirror is a set of multilayer structures
made of alternating layers of high acoustic impedance material and
low acoustic impedance material, for example, Tungsten (W) and
Silicon Dioxide (SiO.sub.2). Table 1 details several potential
materials for fabricating Bragg acoustic mirrors.
[0062] In addition, in at least one embodiment the Bragg acoustic
mirror interoperates with other elements of the design toward
creating a multiband multiferroic antenna array, that is to say a
multiferroic antenna array having different resonant frequencies,
thus expanding the antenna array's bandwidth to wide bandwidths or
even ultra-wide bandwidths.
[0063] Achieving ultra-wide bandwidth antennas requires
electrically small antenna elements to form an antenna array. A
multiferroic antenna is the best suitable antenna element for
airborne platforms because it can avoid platform effects and it is
low-profile. The present disclosure describes a multiferroic
antenna with energy reflecting components, including the Bragg
acoustic mirror and one or more gratings.
[0064] FIG. 11A through FIG. 11D illustrate an example embodiment
230, 240, 250, 260 of a multiferroic antenna structure and
characteristics. In FIG. 11A is seen a structure diagram of an
embodiment 230 of this multiferroic antenna. The antenna 232 is
fabricated with magnetoelastic material, for example Nickel and
FeGaB, and incorporates micro elements and comb-shaped electrodes.
Surrounding the magnetoelastic material micro elements and
comb-shaped electrodes there are acoustic gratings and Bragg
acoustic mirror 234 to reflect the acoustic energy to form a
standing wave and prevent energy dissipation. The magnetoelastic
material micro elements, comb-shaped electrodes and acoustic
gratings are on the top of AlN, which is piezoelectric.
[0065] At the bottom of the AlN layer there is a global ground
electrode. Below the ground electrodes there is a Bragg acoustic
mirror 234 made of high acoustic impedance material and low
acoustic impedance material multilayer. In the example embodiment,
these structures are on top of a substrate (e.g., Silicon),
although they may be on the skin of an airborne platform directly,
or some other structure.
[0066] In FIG. 11B depicts the working principle 240 of the
multiferroic antenna with strips 242a through 242e, comprising
alternating electrodes and magnetoelastic (ME) material. Element
242d is a floating ME material shown as islands between electrodes.
Oscillation of magnetoelastic material micro elements excited by a
free space electromagnetic wave 244 is detected 246 by the
comb-shaped arrays of metallic electrodes through the out-of-plane
electrical field which generates output voltage 248.
[0067] In FIG. 11C characteristics 250 are seen showing a portion
of the antenna 252, the inside 254 of floating ME material and 256
representing a plot of magnetic state in the magnetoelastic
material (e.g., Nickel). Diagram of cross section 254 was
originally in multiple colors depicting the direction of
magnetization but has been rendered to a line drawing to comport
with patent office drawing guidelines. In the plot 256, the x axis
is time, and the y axis is the normalized magnetic component on the
y direction. This strain input is about 80 micro strains (ppm)
oscillating at 400 MHz. This strain input is obtained from a finite
element model with -10 dBm input. Under this input, the strain on
the magnetic elements will be 80 macrostrain (ppm). At the same
time, magnetic components change will from 0.3 to 0.7 (normalized),
which is a 20 percent change. All the data is calculated from a
finite difference simulation implemented using the commercial
software MuMax.
[0068] In FIG. 11D is shown 260 the test setup and expected
radiation power predicted by dipole-dipole calculation if the
antenna's size is 2 cm*2 cm. A depiction of the source 264 and
measured power 262 setup is shown. If it is considered that the
magnetic dipole is rotating, then the far-field radiation power as
seen in plot 266 will be about -27 dBm, as shown by the upper plot
line. This is also the upper limit of the radiation power for an
antenna size of 2 cm*2 cm and the example utilizes Nickel as the
magnetoelastic material. If we use other material like FeGaB, the
radiation power can be improved quadratically. The lower line
depicts radiation power if calculated according to the magnetic
state change in FIG. 11C, then the radiation power is estimated be
around -40 dBm. If the antenna's area is increased, the radiation
power will increase quadratically with the increase in area.
[0069] The calculation of predicted radiation power is briefly
discussed. Continuous circular rotation of the magnetization vector
in a disk, which is constant in magnitude, can be conceptualized as
the linear superposition of two oscillating magnetic dipoles.
Assuming the superposition of horizontal Hertzian dipoles placed 90
degrees apart and oscillating 90 degrees out of phase the component
the total magnetic dipole moment of a turnstile antenna lying on
the x-y plane can be written as:
m=m.sub.o(x+iy)e.sup.-i.omega.t
[0070] The far field electric and magnetic field components are
given as:
E = - Zk 2 4 .times. .times. .pi. .times. .times. r .times. e i
.function. ( kr - .omega. .times. .times. t ) .function. ( r
.times. m o ) ##EQU00001## H = - 1 Z .times. ( E .times. r )
##EQU00001.2## where .times. .times. Z = .mu. o o .times. .times.
and .times. .times. k = w c , ##EQU00001.3##
with c being the speed of light.
[0071] In spherical coordinates (r, .theta.,.phi.) we have:
E = - Zk 2 .times. m o 4 .times. .times. .pi. .times. .times. r
.times. e i .function. ( kr - .omega. .times. .times. t )
.function. ( r .times. x + ir .times. y ) = - Zk 2 .times. m o 4
.times. .times. .pi. .times. .times. r .times. e i .function. ( kr
- .omega. .times. .times. t ) .function. [ sin .times. .times.
.phi. .times. .times. e .phi. + cos .times. .times. .theta. .times.
.times. cos .times. .times. .phi. .times. .times. e .phi. + i
.function. ( cos .times. .times. .phi. .times. .times. e .theta. +
cos .times. .times. .theta. .times. .times. sin .times. .times.
.phi. .times. .times. e .phi. ) ] ##EQU00002## .times. E = - Zk 2
.times. m o 4 .times. .times. .pi. .times. .times. r .times. e i
.function. ( kr - .omega. .times. .times. t ) .function. [ ( sin
.times. .times. .phi. - i .times. .times. cos .times. .times. .phi.
) .times. e .phi. + cos .times. .times. .theta. .function. ( cos
.times. .times. .phi. + i .times. .times. sin .times. .times. .phi.
) .times. e .phi. ] ##EQU00002.2## .times. and .times.
##EQU00002.3## H = - 1 Z .times. ( E .times. r ) = k 2 .times. m o
4 .times. .times. .pi. .times. .times. r .times. e i .function. (
kr - .omega. .times. .times. t ) .function. [ ( sin .times. .times.
.phi. - i .times. .times. cos .times. .times. .phi. ) .times. e
.theta. .times. e r + cos .times. .times. .theta. .function. ( cos
.times. .times. .phi. + i .times. .times. sin .times. .times. .phi.
) .times. e .phi. .times. e r ] .times. .times. H = k 2 .times. m o
4 .times. .times. .pi. .times. .times. r .times. e i .function. (
kr - .omega. .times. .times. t ) .function. [ - ( sin .times.
.times. .phi. - i .times. .times. cos .times. .times. .phi. )
.times. e .phi. + cos .times. .times. .theta. .function. ( cos
.times. .times. .phi. + i .times. .times. sin .times. .times. .phi.
) .times. e .theta. ] ##EQU00002.4##
[0072] The time time-averaged power radiated is then written
as:
dP d .times. .times. .OMEGA. = Zk 4 32 .times. .times. .pi. 2
.times. ( r .times. m ) .times. r 2 = Zk 4 32 .times. .times. .pi.
.times. m 2 .times. sin 2 .times. .theta. ##EQU00003##
[0073] And, finally the total power radiated is given as:
P = Zk 4 12 .times. .times. .pi. .times. m 2 = .mu. o .times.
.omega. 4 12 .times. .times. .pi. .times. .times. c 3 .times. m 2
##EQU00004##
[0074] FIG. 12 illustrates a mechanism for interoperating with the
multiferroic antenna in a time varying antenna embodiment,
exemplified using a switched antenna circuit 270. Switch 272
depicts three different inputs received at an input side as a first
control voltage 274, second control voltage 276 and RF voltage 278.
The RF voltage carries the information for different frequencies.
The RF can be switched 279 between a first RF Out 280 and a second
RF Out 282 which is connected to different multiferroic antennas
that can operate at different frequency ranges. It should be
appreciated that the present disclosure is not limited to using two
output switching but may utilize multiway (n-way) switching with
any desired number of outputs (and inputs), using any desired form
of switching. Because the antenna relies on mechanical resonance,
even after the input stops being received, the antenna can still
output electromagnetic waves for several micro seconds.
Incorporated with fast switches, several antennas that can operate
under different frequencies and can radiate together are combined
in order to expand the frequency range of the whole antenna system
to reach broad band radiation.
[0075] FIG. 13A and FIG. 13B depict simulation results 290, 300
with a finite element model that consists of electrostatics and
solid mechanics modules by solving the equations:
.epsilon..sub.el=s.sub.E:d.sup.tE
D=d:.sigma.+e.sub..sigma.E
where .sigma. is the stress tensor, E is the electric field vector,
s.sub.E is the piezoelectric compliance matrix measured under
constant electric fields, d and d.sup.t are the piezoelectric
coupling matrix and its transpose, and e.sub..sigma. is the
electric permittivity matrix measured under constant stress.
[0076] In FIG. 13A a plot is shown 290 depicting return loss (S22)
in the frequency domain. The x axis shows the frequency range
between 420 MHz to 450 MHz while the y axis shows the return loss
in dB scale. For the first design, the antenna elements can
resonate at 434 MHz and the return loss can reach -13.7 dB. By
changing the antenna's electrode width and other geometry
parameters, the antenna's resonant frequency can be modified as
desired. In this way, antenna elements can be designed from 340 MHz
to 400 MHz to reach the goal for wideband.
[0077] In FIG. 13B is a plot 300 of simulation results for strain
in the time domain on the magnetoelastic material elements. The x
axis shows the time range from 0 to 50 nanoseconds while the y axis
shows the strain. Here, a pulse with a center frequency of 434 MHz
is applied for 10 nanoseconds. However, the strain oscillation
continues and will not decay significantly until time reaches 50
nanoseconds. This indicates that the antenna can still radiate an
electromagnetic wave even after the RF input is cut off, which
makes it possible for integration with switching mechanisms toward
achieving multiband operation.
5. General Scope of Embodiments
[0078] From the description herein, it will be appreciated that the
present disclosure encompasses multiple embodiments which include,
but are not limited to, the following:
[0079] A multiferroic radio frequency antenna apparatus,
comprising: (a) a piezoelectric substrate; (b) at least one pair of
electrodes coupled to said piezoelectric substrate; and (c) a
plurality of magnetoelastic and/or magnetostrictive resonators
coupled to said piezoelectric substrate; (d) wherein said
electrodes in combination with piezoelectric substrate convert
between radio frequency electrical signals input at the electrodes
to mechanical waves in the piezoelectric substrate, or from
mechanical waves in the piezoelectric substrate to radio frequency
electrical signal from the electrodes; (e) wherein said
magnetoelastic and/or magnetostrictive resonators in combination
with said piezoelectric substrate convert between radio frequency
electromagnetic waves input at said magnetoelastic and/or
magnetostrictive resonators to mechanical waves in said
piezoelectric substrate, or from mechanical waves in said
piezoelectric substrate to radio frequency electromagnetic waves
from said magnetoelastic and/or magnetostrictive resonators; and
(f) wherein said antenna apparatus performs reception in response
to converting radio frequency electromagnetic radiation into radio
frequency electrical signals, and performs transmission in response
to converting radio frequency electrical signals into radio
frequency electromagnetic radiation.
[0080] A multiferroic radio frequency antenna apparatus,
comprising: (a) a piezoelectric substrate; (b) at least one pair of
electrodes, coupled to said piezoelectric substrate, and configured
for converting between an electrical signal at the electrodes to
mechanical waves in the piezoelectric substrate, or from mechanical
waves in the piezoelectric substrate to electrical signals at the
electrodes; and (c) a plurality of magnetoelastic and/or
magnetostrictive resonators, coupled to said piezoelectric
substrate, and configured for converting between mechanical waves
in the piezoelectric substrate to electromagnetic waves from the
magnetoelastic and/or magnetostrictive resonators, or from
electromagnetic waves received by the magnetoelastic and/or
magnetostrictive resonators into mechanical waves in the
piezoelectric substrate; (d) wherein said piezoelectric substrate
interfaces between said at least one pair electrodes and said
plurality of magnetoelastic and/or magnetostrictive resonators to
transmit electromagnetic signals by converting radio frequency
electrical signals applied at said electrodes into electromagnetic
waves from the magnetoelastic and/or magnetostrictive resonators,
and to receive electromagnetic signals by converting
electromagnetic waves received at said magnetoelastic and/or
magnetostrictive into radio frequency electrical signals at said
electrodes.
[0081] A multiferroic radio frequency antenna apparatus,
comprising: (a) a piezoelectric substrate; (b) a plurality of
magnetoelastic and/or magnetostrictive resonators coupled to said
piezoelectric substrate; (c) at least one pair of electrodes,
having a first electrode coupled to a first surface plane of said
piezoelectric substrate, and a second electrode coupled to a second
surface plane of said piezoelectric substrate; (d) wherein in
receive mode said plurality of magnetoelastic and/or
magnetostrictive resonators create mechanical waves in response to
being excited into magnetic oscillation by receiving
electromagnetic radiation, and these mechanical waves coupled to
the piezoelectric substrate cause it to generate an electrical
output signal at said electrodes; and (e) wherein in transmit mode
an electrical signal coupled through said electrodes to the
piezoelectric substrate induces mechanical waves directed to said
plurality of magnetoelastic and/or magnetostrictive resonators
which are excited into magnetic oscillation to output
electromagnetic waves.
[0082] A multiferroic radio frequency antenna apparatus,
comprising: a piezoelectric substrate; at least one pair of
electrodes coupled to said piezoelectric substrate; and a plurality
of magnetoelastic and/or magnetostrictive resonators coupled to
said piezoelectric substrate; wherein said electrodes in
combination with piezoelectric substrate convert between radio
frequency electrical signals input at the electrodes to mechanical
waves in the piezoelectric substrate, or from mechanical waves in
the piezoelectric substrate to radio frequency electrical signal
from the electrodes; wherein said magnetoelastic and/or
magnetostrictive resonators in combination with said piezoelectric
substrate convert between radio frequency electromagnetic waves
input at said magnetoelastic and/or magnetostrictive resonators to
mechanical waves in said piezoelectric substrate, or from
mechanical waves in said piezoelectric substrate to radio frequency
electromagnetic waves from said magnetoelastic and/or
magnetostrictive resonators; and wherein said antenna apparatus
performs reception in response to converting radio frequency
electromagnetic radiation into radio frequency electrical signals,
and performs transmission in response to converting radio frequency
electrical signals into radio frequency electromagnetic
radiation.
[0083] A multiferroic radio frequency antenna apparatus,
comprising: a piezoelectric substrate; at least one pair of
electrodes, coupled to said piezoelectric substrate, and configured
for converting between an electrical signal at the electrodes to
mechanical waves in the piezoelectric substrate, or from mechanical
waves in the piezoelectric substrate to electrical signals at the
electrodes; and a plurality of magnetoelastic and/or
magnetostrictive resonators, coupled to said piezoelectric
substrate, and configured for converting between mechanical waves
in the piezoelectric substrate to electromagnetic waves from the
magnetoelastic and/or magnetostrictive resonators, or from
electromagnetic waves received by the magnetoelastic and/or
magnetostrictive resonators into mechanical waves in the
piezoelectric substrate; wherein said piezoelectric substrate
interfaces between said at least one pair electrodes and said
plurality of magnetoelastic and/or magnetostrictive resonators to
transmit electromagnetic signals by converting radio frequency
electrical signals applied at said electrodes into electromagnetic
waves from the magnetoelastic and/or magnetostrictive resonators,
and to receive electromagnetic signals by converting
electromagnetic waves received at said magnetoelastic and/or
magnetostrictive into radio frequency electrical signals at said
electrodes.
[0084] A multiferroic radio frequency antenna apparatus,
comprising: a piezoelectric substrate; a plurality of
magnetoelastic and/or magnetostrictive resonators coupled to said
piezoelectric substrate; at least one pair of electrodes, having a
first electrode coupled to a first surface plane of said
piezoelectric substrate, and a second electrode coupled to a second
surface plane of said piezoelectric substrate; wherein in receive
mode said plurality of magnetoelastic and/or magnetostrictive
resonators create mechanical waves in response to being excited
into magnetic oscillation by receiving electromagnetic radiation,
and these mechanical waves coupled to the piezoelectric substrate
cause it to generate an electrical output signal at said
electrodes; and wherein in transmit mode an electrical signal
coupled through said electrodes to the piezoelectric substrate
induces mechanical waves directed to said plurality of
magnetoelastic and/or magnetostrictive resonators which are excited
into magnetic oscillation to output electromagnetic waves.
[0085] A method of generating electromagnetic radiation at radio
frequencies into free space, comprising: utilizing magnetoelastic
and/or magnetostrictive material as resonators to create or receive
mechanical waves across a piezoelectric substrate to electrodes
upon which an electrical signal is created or received.
[0086] The apparatus or method of any preceding embodiment, wherein
said antenna apparatus is configured for transmitting or receiving
radio frequency electromagnetic radiation.
[0087] The apparatus or method of any preceding embodiment, wherein
dynamic magnetic flux current oscillations in said plurality of
magnetoelastic and/or magnetostrictive resonators are used as a
fundamental source for detecting or radiating radio frequency
electromagnetic waves.
[0088] The apparatus or method of any preceding embodiment, wherein
wavelengths of the mechanical waves in said piezoelectric substrate
are orders of magnitude smaller than wavelengths of the radio
frequency electromagnetic waves which are received or transmitted
from said magnetoelastic and/or magnetostrictive resonators,
allowing said antenna apparatus to be orders of magnitude smaller
than a conventional electromagnetic antenna operating at an
identical radio frequency.
[0089] The apparatus or method of any preceding embodiment, wherein
said electrodes comprise a first electrode coupled to a first
surface plane of said piezoelectric substrate, and a second
electrode coupled to a second surface plane of said piezoelectric
substrate.
[0090] The apparatus or method of any preceding embodiment, wherein
said first electrode or said second electrode is configured in a
pattern with open spaces within each of which are disposed an array
of magnetoelastic and/or magnetostrictive resonators.
[0091] The apparatus or method of any preceding embodiment, wherein
said piezoelectric substrate uses dynamic strain in converting
between electrical signals and mechanical waves.
[0092] The apparatus or method of any preceding embodiment, wherein
said mechanical waves comprise a shear wave.
[0093] The apparatus or method of any preceding embodiment, wherein
said plurality of magnetoelastic and/or magnetostrictive resonators
are configured to transfer between electromagnetic waves and
mechanical waves in response to their natural frequency.
[0094] The apparatus or method of any preceding embodiment, wherein
size, shape, and distance relationships between said plurality of
magnetoelastic and/or magnetostrictive resonators and said
electrodes determine the resonant parameters.
[0095] The apparatus or method of any preceding embodiment, wherein
said electrodes comprise a detector for measuring voltage and
generating an output to a grounded coplanar waveguide.
[0096] The apparatus or method of any preceding embodiment, wherein
said mechanical waves comprise a shear wave, or a shear-horizontal
wave, or a lamb wave, or any combination of shear wave, shear
horizontal wave and lamb wave.
[0097] The apparatus or method of any preceding embodiment, further
comprising incorporating islands of floating magnetoelastic (ME)
material between at least one pair of electrodes.
[0098] The apparatus or method of any preceding embodiment, further
comprising an antenna switching circuit configured for switching m
radio-frequency sources or inputs, between n different multiferroic
antennas in response to receiving at least one control voltage in a
time varying antenna, wherein value n is larger than m.
[0099] The apparatus or method of any preceding embodiment, wherein
at least a portion of said n different multiferroic antennas
operate at different frequency ranges, toward broadening frequency
range of said multiferroic radio frequency antenna apparatus to
reach broad band radiation
[0100] The apparatus or method of any preceding embodiment, further
comprising incorporating mechanical acoustic energy reflecting
mechanisms toward enhancing mechanical wave strength and/or
electrical signal strength.
[0101] The apparatus or method of any preceding embodiment, wherein
said mechanical acoustic energy reflecting mechanisms are selected
from the group of mechanical acoustic energy reflecting mechanisms
consisting of Bragg acoustic mirrors, acoustic gratings, trenches,
and air cavities, toward enhancing mechanical wave strength and/or
electrical signal strength.
[0102] The apparatus or method of any preceding embodiment, wherein
said mechanical waves comprise a shear wave, or a shear-horizontal
wave, or a lamb wave, or any combination of shear wave, shear
horizontal wave and lamb wave.
[0103] The apparatus or method of any preceding embodiment, further
comprising incorporating islands of floating magnetoelastic (ME)
material between at least one pair of electrodes.
[0104] The apparatus or method of any preceding embodiment, further
comprising switching n different multiferroic antennas between m
radio-frequency sources or inputs, in response to receiving at
least one control voltage in controlling a time varying antenna, in
which value n is larger than value m.
[0105] The apparatus or method of any preceding embodiment, wherein
at least a portion of said n different multiferroic antennas are
configured for operating at different frequency ranges than one
another, toward broadening overall an range of operating
frequencies.
[0106] The apparatus or method of any preceding embodiment, wherein
said antenna apparatus is configured for transmitting or receiving
radio frequency electromagnetic radiation.
[0107] The apparatus or method of any preceding embodiment, wherein
dynamic magnetic flux current oscillations in said plurality of
magnetoelastic and/or magnetostrictive resonators are used as a
fundamental source for detecting or radiating radio frequency
electromagnetic waves.
[0108] The apparatus or method of any preceding embodiment, wherein
wavelengths of the mechanical waves in said piezoelectric substrate
are orders of magnitude smaller than wavelengths of the radio
frequency electromagnetic waves which are received or transmitted
from said magnetoelastic and/or magnetostrictive resonators,
allowing said antenna apparatus to be orders of magnitude smaller
than a conventional electromagnetic antenna operating at an
identical radio frequency.
[0109] The apparatus or method of any preceding embodiment, wherein
said electrodes have a first electrode coupled to a first surface
plane of said piezoelectric substrate, and a second electrode
coupled to a second surface plane of said piezoelectric
substrate.
[0110] The apparatus or method of any preceding embodiment, wherein
said first electrode or said second electrode is configured in a
pattern with open spaces within each of which are disposed an array
of magnetoelastic and/or magnetostrictive resonators.
[0111] The apparatus or method of any preceding embodiment, wherein
said piezoelectric substrate uses dynamic strain in converting
between electrical signals and mechanical waves.
[0112] The apparatus or method of any preceding embodiment, wherein
said mechanical waves comprises a shear wave.
[0113] The apparatus or method of any preceding embodiment, wherein
said plurality of magnetoelastic and/or magnetostrictive resonators
are configured to transfer between electromagnetic waves and
mechanical waves in response to their natural frequency.
[0114] The apparatus or method of any preceding embodiment, wherein
size, shape, and distance relationships between said plurality of
magnetoelastic and/or magnetostrictive resonators and said
electrodes determine the resonant parameters.
[0115] The apparatus or method of any preceding embodiment, wherein
said electrodes comprise a detector for measuring voltage and
generating an output to a grounded coplanar waveguide.
[0116] As used herein, the singular terms "a," "an," and "the" may
include plural referents unless the context clearly dictates
otherwise. Reference to an object in the singular is not intended
to mean "one and only one" unless explicitly so stated, but rather
"one or more."
[0117] As used herein, the term "set" refers to a collection of one
or more objects. Thus, for example, a set of objects can include a
single object or multiple objects.
[0118] As used herein, the terms "substantially" and "about" are
used to describe and account for small variations. When used in
conjunction with an event or circumstance, the terms can refer to
instances in which the event or circumstance occurs precisely as
well as instances in which the event or circumstance occurs to a
close approximation. When used in conjunction with a numerical
value, the terms can refer to a range of variation of less than or
equal to .+-.10% of that numerical value, such as less than or
equal to .+-.5%, less than or equal to .+-.4%, less than or equal
to .+-.3%, less than or equal to .+-.2%, less than or equal to
.+-.1%, less than or equal to .+-.0.5%, less than or equal to
.+-.0.1%, or less than or equal to .+-.0.05%. For example,
"substantially" aligned can refer to a range of angular variation
of less than or equal to .+-.10.degree., such as less than or equal
to .+-.5.degree., less than or equal to .+-.4.degree., less than or
equal to .+-.3.degree., less than or equal to .+-.2.degree., less
than or equal to .+-.1.degree., less than or equal to
.+-.0.5.degree., less than or equal to .+-.0.1.degree., or less
than or equal to .+-.0.05.degree..
[0119] Additionally, amounts, ratios, and other numerical values
may sometimes be presented herein in a range format. It is to be
understood that such range format is used for convenience and
brevity and should be understood flexibly to include numerical
values explicitly specified as limits of a range, but also to
include all individual numerical values or sub-ranges encompassed
within that range as if each numerical value and sub-range is
explicitly specified. For example, a ratio in the range of about 1
to about 200 should be understood to include the explicitly recited
limits of about 1 and about 200, but also to include individual
ratios such as about 2, about 3, and about 4, and sub-ranges such
as about 10 to about 50, about 20 to about 100, and so forth.
[0120] Although the description herein contains many details, these
should not be construed as limiting the scope of the disclosure but
as merely providing illustrations of some of the presently
preferred embodiments. Therefore, it will be appreciated that the
scope of the disclosure fully encompasses other embodiments which
may become obvious to those skilled in the art.
[0121] Phrasing constructs, such as "A, B and/or C", within the
present disclosure describe where either A, B, or C can be present,
or any combination of items A, B and C. Phrasing constructs
indicating, such as "at least one of" followed by listing group of
elements indicates that at least one of these group elements is
present, which includes any possible combination of these listed
elements as applicable.
[0122] References in this specification referring to "an
embodiment", "at least one embodiment" or similar embodiment
wording indicates that a particular feature, structure, or
characteristic described in connection with a described embodiment
is included in at least one embodiment of the present disclosure.
Thus, these various embodiment phrases are not necessarily all
referring to the same embodiment, or to a specific embodiment which
differs from all the other embodiments being described. The
embodiment phrasing should be construed to mean that the particular
features, structures, or characteristics of a given embodiment may
be combined in any suitable manner in one or more embodiments of
the disclosed apparatus, system or method.
[0123] All structural and functional equivalents to the elements of
the disclosed embodiments that are known to those of ordinary skill
in the art are expressly incorporated herein by reference and are
intended to be encompassed by the present claims. Furthermore, no
element, component, or method step in the present disclosure is
intended to be dedicated to the public regardless of whether the
element, component, or method step is explicitly recited in the
claims. No claim element herein is to be construed as a "means plus
function" element unless the element is expressly recited using the
phrase "means for". No claim element herein is to be construed as a
"step plus function" element unless the element is expressly
recited using the phrase "step for".
* * * * *